epoll

问题 epoll in edge trigger mode is a strange beast. It requires the process to keep track of what the last response for each monitored FD is. It mandates the process to handle, without fail, each and every event reported (or else we might think that an FD is not reporting anything whilst it is, in fact, muted by the edge trigger behavior). When does it make sense to use epoll this way? 回答1: The main use case for EPOLLET that I'm aware of is with micro-threads. To recap - user space is doing

问题 I want to write an event based server using epoll. each client has a distinct request, and the server should respond to them. the server will wait for connections, and when connections are available they're queued for read. data is read from the clients and they'll be queued for write. after processing the data, an appropriate response should be sent to each. all the operations will be asynchronously. the problem is, how can I determine, which response is for which socket when the sockets are

问题 Is it possible to use zmq.Poller to also poll for data availability on stdin ? If not, what would be the most efficient wait to poll, at the some time (ideally), for data availability on zeromq sockets & stdin ? 回答1: yes, zmq pollers do support native FDs, including stdin, etc., so you just need to check sys.stdin.fileno() : poller = zmq.Poller() poller.register(sys.stdin, zmq.POLLIN) poller.register(mysocket, zmq.POLLIN) evts = dict(poller.poll(1000)) stdin_ready = evts.get(sys.stdin.fileno(

问题 In epoll usage, it is usually like the following: struct epoll_event ev,events[20]; epfd=epoll_create(256); 。。。 nfds=epoll_wait(epfd,events,40,500); Some articles are saying that the maxevents parameter in epoll_wait (namely the 40 in epoll_wait(epfd,events,40,500); ) should not exceed the size parameter in epoll_create (namely the 256 ). I think the maxevents parameter should not exceed 20 in ev, events[20] , because events can only be registered to 20 events elements; otherwise, if there

问题 My epoll_wait fails due to EINTR. My gdb trace shows this: enter code here 221 in ../nptl/sysdeps/pthread/createthread.c (gdb) 224 in ../nptl/sysdeps/pthread/createthread.c (gdb) [New Thread 0x40988490 (LWP 3589)] 227 in ../nptl/sysdeps/pthread/createthread.c (gdb) epoll_wait error in start timer: Measurement will befor entire duration of execution epoll_wait: Interrupted system call [Thread 0x40988490 (LWP 3589) exited] This string "epoll_wait error in start timer: Measurement will befor

问题 I am using native epoll transport in netty and was able to download netty-transport-native-epoll-4.0.32.jar from the repository. However I also need netty-transport-native-epoll-4.0.32.Final-linux-x86_64.jar but not unable to find it anywhere. Please let me know where to download this jar, or how to build it. 回答1: The file can be found here : http://repo.scub-foundation.org/artifactory/libs-release/io/netty/netty-transport-native-epoll/4.0.32.Final/ The content doesn't seem to be different

问题 I am working on a network programming using epoll. I have a connection list and put every client in the list. I can detect user disconnection by reading 0 if the user disconnected normally. However, if the user somehow got disconnected unexpectedly then there is no way it knows about this until it tries send data to the user. I don't think epoll provides a nice way to handle this..so I think I should handle this on my own. I will be very appreciated if you guys can provide me anything like

问题 Wikipedia says unlike the older system calls, which operate at O(n), epoll operates in O(1) [2]). http://en.wikipedia.org/wiki/Epoll However, the source code at fs/eventpoll.c on Linux-2.6.38, seems it is implemented with an RB tree for searching, which has O(logN) /* * Search the file inside the eventpoll tree. The RB tree operations * are protected by the "mtx" mutex, and ep_find() must be called with * "mtx" held. */ static struct epitem *ep_find(struct eventpoll *ep, struct file *file,

问题 I'm currently adding sockfds created from accept to an epoll instance with the following events: const int EVENTS = ( EPOLLET | EPOLLIN | EPOLLRDHUP | EPOLLONESHOT | EPOLLERR | EPOLLHUP); Once an event is triggered, I pass it off to a handler thread, read and then re-enable the sockfd through epoll_ctl with the same flags. However, I only receive the EPOLLIN event one time. Also, if I kill the client anytime after the first event is received, I do not get hangup events either. From reading

问题 The following code essentially cats a file with select.select(): f = open('node.py') fd = f.fileno() while True: r, w, e = select.select([fd], [], []) print '>', repr(os.read(fd, 10)) time.sleep(1) When I try a similar thing with epoll I get an error: self._impl.register(fd, events | self.ERROR) IOError: [Errno 1] Operation not permitted I've also read that epoll does not support disk files -- or perhaps that it doesn't make sense. Epoll on regular files But why does select() support disk